Heretofore, pressure gauges were commonly used to measure the pressure in pressurized systems. However, as control systems have become increasingly automated, it has become more useful and convenient to convert the line pressure into a proportional voltage or current.
Typically, a conversion from pressure into an equivalent voltage or current involves a diaphragm which moves in accordance with the line pressure exerted against it. The diaphragm may actuate a strain gauge or other electrical device to provide the required current or voltage. The current or voltage which is generated by the movement of the diaphragm is usually too small to be useful in its initial form and so amplification is required. A convenient way to do this is to utilize a chopper stabilized DC amplifier. All this, however, involves some rather complex circuitry, and when the transducer is mounted in a housing along with the circuitry, periodic servicing or replacement is required. If servicing is required, it would be desireable to be able to perform it as easily as possible without any disruption of the line pressure, or leakage of the pressurized contents in the line into the ambient air.
What is needed, therefore, and comprises an important object of this invention, is to provide a pressure transducer which can be quickly and easily connected or disconnected from a pressurized line without disturbing the line pressure.